Liquid level indicator



Oct. 18, 1955 R. K. SEDGWICK LIQUID LEVEL INDICATOR Filed Dec. 28, 1951 IN V EN TOR.

Roerf Sefigwicff United States latent LIQUID LEVEL INDICATOR Robert K. Sedgwick, Sharonville, Ohio, assignor to American Steel Foundries, Chicago, lll., a corporation of New Jersey Application December 28, 1951, Serial No. 263,823 7 Claims. (Cl. 73-314) This invention relates to a level indicator for a liquid retaining vessel wherein the pressure is substantially greater or less than atmospheric as, for example, an air ballasted accumulator vessel such as is commonly utilized in hydraulic supply systems for hydraulic presses, and the like, wherein actuating pressures of the order of one to three thousand pounds per square inch are developed.

Prior art indicators for such vessels have generally been one or the other of two types. The iirst type comprises a glass tube connected to the vessel so that the level of liquid in the tube is approximately the same as that in the vessel. Such indicators have generally been unsatisfactory due not only to the possibility of breakage, but also to adherence of hydraulic mediums, such as oil, on the inside of the tube, thereby rendering the same substantially opaque.

The second prior art type of level indicator for pressure vessels has utilized a magnetic iloat supported by the liquid in the pressure vessel or in a communicating vessel, in combination with external mechanical means responsive to the magnetic field of the iloat. Such mechanical means have been in the form of rollers or arrows within the path of the magnetic eld during movement of the lioat in response to changes of liquid level.

However, such prior art mechanical indicators responsive to magnetic floats have generally been unsatisfactory due to the inuence of impacts and vibrations thereon, as well as to mechanical impediments, such as rust and collection of dust.

A primary object of the present invention is to devise electrical means responsive to a magnetic float, such as above described, in order to eliminate the undesirable characteristics of prior art mechanical indicators.

A further object of the invention is to devise electrical means which are visually responsive to changes in the position of the magnetic oat thereby eliminating any necessity for Calibrating electrical gauges or the like.

A more specic object of the invention is to provide an electrical arc which is disturbed by the magnetic field of the oat and is positioned in the path of said eld as the tloat moves upwardly and downwardly in response to variations of the liquid level in the container.

The foregoing and other objects and advantages of the invention will become apparent from a consideration of the following specilication and the accompanying drawings, wherein:

Figure 1 is a somewhat diagrammatic view partly in central, vertical section of a liquid level indicator embodying the invention;

Figure 2 is an enlarged sectional view on the line 2 2 of Figure 1;

Figure 3 is a side elevational view partly in central vertical section of the magnetic float utilized in Figures 1 and 2, and

Figure 4 is a side elevational view of the oat taken from the right, as seen in Figure 3.

Describing the invention in detail, an accumulator vessel or container, generally designated 2, is provided Patented Oct. 18, 1955 ice with an outlet line 4, adapted to convey hydraulic fluid such as water or oil to an associated device for using such iluid as, for example, an hydraulic press. The vessel 2 is preferably of the air ballasted type which is conventional in the hydraulic press art and contains a body of hydraulic uid 6 and a charge of pneumatic pressure iluid 8 under maximum pressure of the order of three thousand pounds per square inch.

The vessel 2 is preferably connected by top and bottom pipes or conduits 10 and 12, to a hollow, substantially vertical column or container 14 so that the level of hydraulic fluid in the column 14 is approximately the same as the level of the hydraulic uid within the vessel 2. The column 14 may be formed of any desirable nonmagnetizable opaque material, such as, for example, stainless steel, aluminum or plastic, depending upon the maximum pressure within the system. The liquid within the column 14 is adapted to support a lloat, generally designated 16 and comprising a tube 18 sealed by a cap 20 having a U-shaped bracket 22 confining a preferably permanent magnet 24, which is releasably clamped against the cap 20 as, for example, by means of a set screw 26. It may be noted that, if desired, the magnet 24 may be formed as an integral part of the cap 2i) or of any other portion of the oat 16, the illustrated embodiment being by way of example. Furthermore, the oat 16 may be of any desired type, the design of which will necessarily vary depending upon the maximum pressure value within the accumulator vessel 2.

A transparent tube 28 formed of any suitable material such as, for example, glass, is supported by top and bottom spring clamps 30 and 32, which may be conveniently mounted on the side of the column 14 so that one of the north and south poles of the magnet 24 faces the tube 23, said poles being designated N and S, respectively. It may be noted, in this connection, that the column 14, may be of any desired shape and is illustrated as square in Figure 2, in order to limit rotation of the iloat 16 thereby maintaining one pole of magnet 24 in facing rela tionship with respect to the tube 28, as shown in Figure 2.-

The tube 23 is lled with an inert gas such as argon, carbon dioxide, helium, krypton, neon, nitrogen or xenon under subatmospheric pressure of, for example, 3 centimeters Hg. Electrodes 34 and 36 at opposite ends of the tube 2S are connected to leads 38 and 40 of a conventional transformer 42, whereby the electrodes 34 and 36 Y conduct electrical current through the inert gas in the tube 28 to form a normally substantially straight arc or light line 44. Thus the tube 28 and its contents constitute what is ordinarily known as a neon lght; however, that termA as used in the specification and the claims hereof is hereby defined as including any light wherein electrical current passes through a gaseous medlum to define a light line or arc which is disturbed by a magnetic field.

In this connection it may be noted that such an arc occurs when the inert gas in the tube 28 is at a subatmospheric pressure of about l to 3 centimeters Hg, the electrical discharge taking the form of a ribbon of light down the middle of the tube. At pressures higher than that at which such a ribbon appears, the light becomes stringy and ilickering and finally disappears as the density of the gas reaches a value at which the current cannot pass between the electrodes. At atmospheric pressure enormous voltages are required to transmit current between electrodes and the resulting discharge resembles a bolt of lightning. At lower pressure than that at which the visible ribbon or arc is visible as, for example, in tubes containing gas under a pressure of a few millimeters Hg, the entire tube is lled with light and an arc is not discernible. For this reason, as above noted, the term neon light or neon tube, as used in the specification and claims hereof, is limited to a light wherein the current and gasvpressureare so proportioned as to define a visible light line or arc inthe form of a ribbon. Such a ribbon when intersected by a magnetic field develops' a clearly visible oiset or disturbance,as

shown at 46in Figure 1 of the drawings. Y V Y Y Y As best'seen iny Figure 1, the light line 44 is oiset as at 46, from its normal straight path between the elec-r trodes 34 and 36, said offset 46 being VVeiected by the magnetic eld of the magnett24 which, as best seen in Figure 1, is in horizontal alignment vwith the disturbance 46, Thus it will be understood, as the iioatrl moves upwar'dlyandV downwardly within the column 14 in respouse to changes of the level of hydraulic fluid 6 within the accumulator Vvessel 2, the disturbance`46`moves upwardly Vand downwardly in unison with the magnet 24, thereby afording a positive external, visual indicia of the level of hydraulic fluid 6 within the vessel 2.

It may be noted that although they novel device is particularly useful, asy in the illustrated embodiment, for indicating the Ylevel of liquid within an opaque container, the device may also be used to indicate the vposition of any movable member behind an opaque partition such t as, for example, the column 14 illustrated in the drawings.

I claim: Y Y

l. A liquid level indicator for indicating the variable level of liquid within an opaque non-magnetizable conf tainer, said indicator comprising a oat supported by said liquid, a magnet movable with the oat, and an energized neontube adjacent said container and passing through the magnetic field of the magnet and extending between vertically spaced levels corresponding to the variable levels of the liquid in said container whereby movement of said magnet between said levels inr response to movement of said iioat is indicated by disturbance ofV the light line in said tube. Y Y t, Y

2.Y A liquid level indicator for indicating the variable level of liquid in an opaque non-magnetizable container,

Y said indicator comprising a float supported by said liquid,

a magnet connected to the iioat for movement in response 'Y to movement of said oat, and an electric arc externally VVof the container and extending between vertically yspaced pointstexternally thereof, said pointsY approximately corresponding to the variable levels of theliquid in said container, said varc being intersected by the magnetic eld of the magnet whereby the latter produces` a visible disturbance in the` arc atapoint correlated to the then levelof the liquid.

Y 3. In a liquid level indicator `for indicating the level of V liquid in an opaque non-magnetizable container; the combination ofa oat supported by said liquid, a magnet connected to the tloat for movement therewith in response yto change of the liquid level in said container, and an energized neonv tube externally ofthe container intersecttainer, and magnetic iioat means tioatably supported by said liquid for developing a magnetic iield intersecting said arc and effecting a visible disturbance vtherein at a point correlated to the then level of the liquid.

5. An indicator for indicating the position of a movable Y member at one side of a substantially opaque non-magnetizable partition, said indicator comprising a visible electric arc at the other side of said partition, and mag-V net means disposed at said one side of saidV partition and movable lengthwise of said arc in response tovchange Vin position of said membenrsaid magnet means developing a magnetic eld vextending through the partition andL intersecting'the arc and effecting a visible disturbance in the arc at a point correlated to the thenposition of the member, wherebyV a change in Ypositionof said member causes. a corresponding change in positionV of said disturbance. Y

Y 6. An indicator for indicating the position of a mem` ber at one side of a substantially opaque nonfmagnetb,

able partition, saidtindicator comprising aneon light at the opposite side of said partition, and magnet means dis'- posed at said one side of said partition and movable in unisonjwitlr said member lengthwise of said light, said magnet means developing a magnetic ield extending n through the partition and intersecting said lightrto create Y a point of visibleV disturbance therein correlated to the then position of said member.

7. An indicator for indicating the level of liquid within -an opaque non-magnetizable container, said indicator comprising means oating in said liquid, a' visible electric arc externally oi?` said container and extending between points locatedadjacent desired maximum and minimum levels Vof said liquid, and means supported by said oating means `for developing a magnetic eld which intersects the arc and creates a visible point of disturbance in saidA arc correlated to the level of liquid in the container..

References Cited in the file of this patent UNTTED STATES PATENTS 2,182,469 Davis Y Dec. 5, 1939 2,233,572` Atkins Mar. V4,'1941 2,383,758 Ziebolz Aug. 28, 1945 LDe Giers et al Sept. 27, 1949 

